Molecular diagnosis and genotyping of Clostridium difficile

Abstract

Clostridium difficile was first discovered in 1935, but it was not until 1977 that this bacterium was found to be associated with pseudomembranous colitis. The disease was considered to be caused by the production of two C. difficile toxins, toxins A and B (TcdA and TcdB). TcdA was shown to exhibit enterotoxic effects on the intestine, whereas TcdB was shown to be more cytotoxic. Strains of C. difficile that do not produce these toxins are known to be non-toxinogenic and therefore non-pathogenic. However, outbreaks and more severe infections due to strains producing only TcdB have been described. To diagnose C. difficile -associated disease, a method with a high sensitivity and specificity is necessary. This thesis describes the application of methods based on the molecular detection of the pathogen in comparison with conventional microbiological methods. After isolation of the pathogen, the epidemiology of C. difficile -associated disease can be studied using molecular typing methods on the isolates. These typing methods need to be highly discriminatory, depending on the epidemiological data to be studied, and methods need to be stable en reproducible, with the possibility to exchange data between different laboratories all over the world.